Flow forcing by AC electro-osmosis (ACEO) is a promising technique for actuation and
manipulation of microflows. Utilisation to date mainly concerns pumping and mixing. However, emerging micro-fluidics applications demand further functionalities. The present study explores first ways by which to systematically realise this in three-dimensional (3D) microflows using ACEO. This exploits the fact that continuity “organises” Lagrangian fluid trajectories into coherent structures that geometrically determine the transport properties. 3D Lagrangian flow structures typically comprise families of concentric (closed) streamtubes, acting both as transport barriers and transport conduits, embedded in chaotic regions. Representative case studies demonstrate that ACEO, possibly in combination with other forcing mechanisms, has the potential to tailor these features into multi-functional Lagrangian flow structures for various transport purposes. This may pave the way to “labs-within-a-channel” that offer the wide functionality of labs-on-a-chip yet within one microflow instead of within an integrated system.

Description:

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.